Multifold Enhancement of Dielectric Constant with Improved Flexibility and Transparency of Organic Polar Additive-Modified Poly(vinyl alcohol) Film Through Molecular Weight Optimization

Flexible high-dielectric constant polymer blends have potential in energy storage, sensing, and dielectric applications due to their ease of fabrication and low cost. Conventional strategies typically rely on the incorporation of ceramic or conducting fillers, which often induce aggregation, structural defects, and brittleness, thereby compromising the mechanical flexibility and optical transparency of the blends. Here, an alternative approach is demonstrated, where organic polar molecules are cross-linked within the polymer matrix to achieve simultaneous enhancement of the dielectric constant, flexibility, and transparency by reducing the crystallinity of the polymer blend through the proper selection of both a polymer and an additive of a specific molecular weight, followed by an optimization process. Remarkably, the incorporation of low molecular weight polar additives leads to a dielectric constant enhancement of approximately 3000-fold compared to the pure polymer at 1 Hz. The resulting films exhibit high optical transparency (>85%), excellent stretchability (breaking strain >600%), and thermally stable dielectric behavior. This study presents a perspective for the design of high dielectric constant polymer, thus facilitating advancement in energy storage, sensing, and wearable electronics.